The British Airports Authority - BAA - says that individual airlines are responsible for the management and security of baggage.

So, if your luggage does go missing, it's absolutely vital to report it straight away to the lost baggage desk at the airport.

You'll need to fill in a form - but your bags may not be officially declared lost for three weeks.

British Airways says it asks customers for the make, model and colour of their bags - and the receipt they were given at check-in.

It then gives each customer a ten digit reference number, so they can check on the progress of their search either by phone or online.

If a bag still hasn't turned up after 21 days, it's officially declared lost. And you then have a further week to make a claim.

A more complicated question can be who pays for lost valuables?

The airlines say their liability is limited by the Montreal Convention - to around £800 compensation per person.

British Airways advises customers to claim on their own travel insurance. But many people may find that that their policies do not cover valuables put into baggage stowed in the hold.

And British Airways' website also says it won't accept liability for valuables such as computers and jewellery which go into the hold - which could leave customers in a black hole.

Alice Beer's tips

You can never completely guarantee that your luggage won't go missing, says Alice, but there are some extra things you can do to help keep it safe:

Don't panic: your bags may well turn up, says Alice

Keep your packing list: you can use it as an inventory if the worst happens

Put a piece of paper INSIDE each piece of luggage with your name and contact details on it, in case the label falls off the outside of your bag (don't put your house keys in the same bag).

If you do need to go shopping on holiday to replace missing clothes, remember the compensation limit is £800: this is not a moment to go designer mad.

Consider a service such as Flymycase, which will transport your luggage anywhere in the world for a small fee.

If you're a British Airways passenger specifically, your absolute last chance might be to try the auction house Greasbys in Tooting, South London which sells off unclaimed BA luggage, among other things

All laptops and large electrical items must be removed from the bag and placed in a tray so they can be seen properly

Pushchairs and walking aids are permitted but must be x-ray screened. Wheelchairs are permitted but must be thoroughly searched.

Passengers on transatlantic flights will be searched again at the departure gates. Any liquids, including those bought airside will be confiscated.

The Department for Transport say they will work closely with operators to introduce these new arrangements, seeking to keep disruption to passengers to a minimum. They say they will keep these measures under review.

If passengers have any questions on their travel arrangements or security in place at airports they should contact the airport or their airline.

Airport operator BAA has asked passengers not to bring hand baggage until the latest changes have been phased in at Heathrow, Gatwick and Stansted.

OTHER USEFUL INFORMATION

Delays and cancellations are still affecting flights, especially from the airports around London. If you're due to travel today, check with your airline or with the airport itself.

Please note that the airports are saying that hand luggage won't be allowed until at least this afternoon.

British Airports Authority (BAA)This will give you advice on what's happening at London Heathrow, Gatwick, Stansted airports. It also has links for Glasgow, Edinburgh, Aberdeen and Southampton.